Workpiece cutting method

Abstract

An object cutting method includes: a first step of preparing an object; a second step of irradiating the object with a laser light to form at least one row of modified regions in a single crystal silicon substrate of the object so as to extend between the at least one row of modified regions and a second main surface of the object along each of a plurality of lines to cut and to form a fracture; and a third step of, after the second step, performing dry etching on the object from the second main surface side to form a groove opening to the second main surface, along each of the plurality of lines to cut. In the second step, the modified region is formed so that a not-fracture region, to which the fracture does not extend, is formed at a predetermined position in the thickness direction in the object.

1 . An object cutting method, comprising:
 a first step of preparing an object to be processed including a single crystal silicon substrate and a functional device layer provided on a first main surface side;   a second step of, after the first step, irradiating the object with a laser light to form at least one row of modified regions in the single crystal silicon substrate along each of a plurality of lines to cut and to form a fracture in the object so as to extend between the at least one row of modified regions and a second main surface of the object along each of the plurality of lines to cut; and   a third step of, after the second step, performing dry etching on the object from the second main surface side to form a groove opening to the second main surface, in the object along each of the plurality of lines to cut,   wherein in the second step, the modified region is formed so that a not-fracture region to which the fracture does not extend is formed at a predetermined position in a thickness direction in the object.   
     
     
         2 . The object cutting method according to  claim 1 , wherein the modified region includes at least a first modified region on the first main surface side from the predetermined position and a second modified region on the second main surface side from the predetermined position, and
 in the second step, the first modified region and the second modified region are formed in the single crystal silicon substrate so as to form at the predetermined position the not-fracture region where the fracture extending from the first modified region does not extend to the fracture extending from the second modified region or the not-fracture region where the fracture extending from any one of the first modified region and the second modified region does not extend to another one of the first modified region and the second modified region.   
     
     
         3 . The object cutting method according to  claim 1 , wherein in the second step, the at least one row of modified regions is formed along each of the plurality of lines to cut by forming a plurality of modified spots arranged along each of the plurality of lines to cut, and the fracture is formed to extend between the modified spots adjacent to each other among the plurality of modified spots. 
     
     
         4 . The object cutting method according to  claim 1 , wherein in the third step, the etching ends between a time when the groove reaches the second main surface side of the not-fracture region and a time when the groove reaches the first main surface side of the not-fracture region. 
     
     
         5 . The object cutting method according to  claim 1 , wherein in the third step, the etching is performed to form the groove which has a curved portion at the position of the not-fracture region and has a V-shaped cross section or a U-shaped cross section. 
     
     
         6 . The object cutting method according to  claim 1 , further comprising: a fourth step of, after the third step, cutting the object into a plurality of semiconductor chips along each of the plurality of lines to cut by sticking an extension film to the second main surface side and extending the extension film. 
     
     
         7 . The object cutting method according to  claim 2 , wherein in the second step, the at least one row of modified regions is formed along each of the plurality of lines to cut by forming a plurality of modified spots arranged along each of the plurality of lines to cut, and the fracture is formed to extend between the modified spots adjacent to each other among the plurality of modified spots. 
     
     
         8 . The object cutting method according to  claim 2 , wherein in the third step, the etching ends between a time when the groove reaches the second main surface side of the not-fracture region and a time when the groove reaches the first main surface side of the not-fracture region. 
     
     
         9 . The object cutting method according to  claim 3 , wherein in the third step, the etching ends between a time when the groove reaches the second main surface side of the not-fracture region and a time when the groove reaches the first main surface side of the not-fracture region. 
     
     
         10 . The object cutting method according to  claim 2 , wherein in the third step, the etching is performed to form the groove which has a curved portion at the position of the not-fracture region and has a V-shaped cross section or a U-shaped cross section. 
     
     
         11 . The object cutting method according to  claim 3 , wherein in the third step, the etching is performed to form the groove which has a curved portion at the position of the not-fracture region and has a V-shaped cross section or a U-shaped cross section. 
     
     
         12 . The object cutting method according to  claim 4 , wherein in the third step, the etching is performed to form the groove which has a curved portion at the position of the not-fracture region and has a V-shaped cross section or a U-shaped cross section. 
     
     
         13 . The object cutting method according to  claim 2 , further comprising: a fourth step of, after the third step, cutting the object into a plurality of semiconductor chips along each of the plurality of lines to cut by sticking an extension film to the second main surface side and extending the extension film. 
     
     
         14 . The object cutting method according to  claim 3 , further comprising: a fourth step of, after the third step, cutting the object into a plurality of semiconductor chips along each of the plurality of lines to cut by sticking an extension film to the second main surface side and extending the extension film. 
     
     
         15 . The object cutting method according to  claim 4 , further comprising: a fourth step of, after the third step, cutting the object into a plurality of semiconductor chips along each of the plurality of lines to cut by sticking an extension film to the second main surface side and extending the extension film. 
     
     
         16 . The object cutting method according to  claim 5 , further comprising: a fourth step of, after the third step, cutting the object into a plurality of semiconductor chips along each of the plurality of lines to cut by sticking an extension film to the second main surface side and extending the extension film.